Yes. You go to Cashback rewards website via the link in your online Rogers credit card account and select Apply to Next Transaction Only ( Disabled by default).
Then you make a $20+ transaction so that the accumulated cashback can be applied towards that purchase. If you have more cashback rewards than that purchase, you need to re-enable it( repeat the step above) so it can be used towards the next purchase.
There appears to be a retroactive option now as well which I have never personally utilized yet. My comments above explain the second option in the quote below.
How to redeem cash back rewards towards a purchase you've already made:
(only available with app)
Open the Mastercard® Pay with Rewards™ app on your phone. To download the app, search for 'Pay with Rewards' in the App Store or in Google Play.
Select the 'Redeem' tab to see your purchases in the past 90 days.
Select an eligible purchase (in yellow) and click redeem.
How to instantly redeem cash back rewards towards your purchase:
(available with app and online)
Enable Pay with Rewards for 'Next Only' transaction to redeem every time you have a minimum of $20 in cash back rewards.
Your eligible purchase must be a minimum of $20. If you would like to change your 'Purchase Minimum', enter a new amount greater than $20.
Your cash back rewards will automatically be applied to your account as a credit when you make your next purchase.